History - AustralianAustralian CultureAustralian IdentityAustralian animalsCultural Comparisons Between Australia and other CountriesAustralian Prehistory

Australian Environmental Issues

A true-blue battler

Box jellyfish
How to avoid the stings and what to do if stung

So you wrestle crocs...

Unfairly judged in killing off the thylacine?

The wise little gnomes of Australia

Victors of the great Emu war

Shaping everything from how Australians speak to how they salute

Funnel Web spider
Yyou'll never leave your ugg boots outside

Most herbivores don't grow a spine until they are the size of an elephant. Not so the roo.

Kill less people than cows

Shark attack Australia
How to ensure you don't go by the name of Bob

Tasmanian Devil
The solution to mainland extinctions?

Tasmanian Tiger
A sad tale

Keg of muscle

The mainland's largest marsupial carnevore

Mythical creatures
Yowies and dropbears; some say they are myths but those who are not afraid to talk have shared their stories






Is the Cultural Tide Turning on Willows...Again?

Realising the problem of using science to justify the ideology rather than change the ideology to match the science

Sometimes you really have to feel for farmers. From the 1950s to the 1980s, scientists working for government agencies encouraged farmers to plant willows along water courses to slow erosion. Then in the 1990s, willows became victims of the patriotic ideology that took over Australian science. Farmers found themselves being told to kill the willows and replace them with gum trees.

There was little-to-no research showing that willows had failed to reduce erosion or caused problems that had negatively impacted on biodiversity, fish stocks or agricultural productivity. Nor was there research showing that an alternative species could do a superior job to a willow. Instead, it seems someone made an argument that willows were not native and therefore they should be removed. This argument found a receptive audience in an environmental culture that sees the destruction of non-natives as a kind of rallying patriotic cry. Subsequently, very unscientific arguments were made to justify their removal. These arguments were not supported by research showing how removal of willows would increase agricultural output nor research into the effect of willows on fish assembly. Admittedly, there was research showing that willows transpired more water than gum trees; however, the statistics showing extra water use didn't factor in the ability of willows to lower water temperature to reduce evaporation or stifle the spread of bushfires fuelled by gum trees. Furthermore, research showed that it was on in-stream willows that used more water. A willow on the side of the bank would use a comparable amount of water to a gum tree.

For farmers, the potential of willows to rehydrate land was not considered. For the fishing industry, the potential of willows to decrease the chance of mass fish kills by reducing blackwater events, blue-green algae outbreaks, water temperatures rises or bushfires was not considered. Despite the lack of supporting research, the lobbying succeeded in law changes that saw the willow designated as a “invasive pest.”  With laws passed, making a coherent argument, demonstrating research or referencing real world examples became less important for the activists as they could just refer to the law to justify their position.

After 30 years of pulling out willows, culture appears to again be turning. In 2016, the Mulloon Creek farm near Braidwood in New South Wales was recognised by the United Nations as an example of sustainable farming practice for its use of Natural Sequence Farming. The farm made heavy use of willows to trap water in the land, much to the criticism of neighbours who wanted native plants instead. Evidence showed that more water was distributed into the landscape, the water table was raised, carrying capacity increased by 60% and more water flowed out of the creek at the end of the property than at the beginning. (1) This all happened in one of the worst draughts in recent times. In contrast, there have been some high profile disasters following the removal of willows. In Tasmania in 2014, farmer John Sadler claimed he lost thousands of tonnes of top soil after willows were removed and the replacement vegetation failed to take hold causing soil to fall into the river and be washed out to sea. (2) In 2018, residents of Wagga Wagga called for the replanting of extracted willows after their lake kept suffering extreme blue-green algae blooms. (3)

While having a native plant is one expression of patriotism, it is somewhat of a deluded expression of patriotism if it also reduces biodiversity, decreases productivity and just leaves the laid stripped or burnt bare and the rivers dead.



(Degraded bank on Inglis River in 2014 10 years after removal of willows)

Why willows got a bad reputation

It sounds strange but government departments responsible for maintaining Australia’s recreational freshwater fishing industry supported the removal of willows without any research into how willows affected assembly. According to Sylvia Zukowski and Ben Gawne who conducted a literature review for Murray-Darling Freshwater Research Centre in 2006, such research has never been done. (4)

Without research to fall back on, a patriotic NSW Department of Primary Industries (DPI) defined the problem as a simple case of farmers putting their own needs before the needs of native fish and plants. The criticism of farmers was based largely on evidence that fallen red gum snags are a favoured site for spawning for cod. In its own words,

"Introduced to provide erosion protection and fodder for stock, little thought was given to potential spread and their negative influence on native plants and animals.

Since native fish prefer a red gum over a willow, the fact that willows can be a good source of overhanging canopy cover for half the year is barely worth listing as an advantage." (5)

There was a high degree of stupidity in what the DPI was saying. Specifically, it was saying that since cod prefer sunken red gum logs for spawning, willows needed to be eradicated even though they provided shade and protection. Unfortunately, gums live between 500 to 1000 years so it wouldn’t be for another 500 to 1000 years that cod would get their spawning sites. While an over hanging willow tree will not provide a spawning site that endures as long as a gum, at least it provides something while the cod wait their 500 to 1000 years for the gum trees planted by the DPI to grow and die.

It really was the type of comment that demonstrated that perhaps some research might have been useful before spending tens of millions of dollars to remove a species so embedded in the ecology of many Australian streams. If the research had been done and results showed the cod numbers had not increased after planting gum trees, the DPI would have quickly realised that planting red gums trees next to the river does not in fact increase spawning sites for cod in the river and wont for centuries to come.

The CSIRO has been somewhat inconsistent in its justifications to remove willows. Some of their publications are obviously driven by patriotism that is expressed with the love of gum trees. For example, In 2018, Melissa Lyne wrote for the CSSIRO the page “Managing out Water Spoiling Pests”: (6)

“The loss in many areas of the great river red gum has reduced food sources, such as gum flowers, and taken away habitats for native mammals, reptiles, fish and birds.

The deep canopy of willows also blocks sunlight from reaching the water, making the water colder, and changing the stream ecology.”

Other CSIRO publications were a bit more practical and focussed on water usage. One publication analysed willows and red gums in various positions along water courses. According to the figures, a stream with a willow on the bank will lose about a third of the water through transpiration and evaporation as a river that has no canopy cover. This is roughly the same as a red gum on the side of the stream. In other words, no difference. This led the CSIRO to conclude,

“culling willows from water-limited environments such as river banks is unlikely to generate water savings.” (7)

Although the research found that willows on the bank used a comparative amount of water as a red gum, it found in stream willows resulted in almost two thirds more water loss than evaporation from open water and almost five times as much as a red gum or willow on the bank.

Another guide Controlling Willows Along Australian Rivers: River and Riparian Land Management Technical Guideline, Land and Water Australia (8), proposed willows should be removed because:
    1. Are invasive and can block the water flow causing flooding
    2. Use more water than native plants
    3. Willow roots spread into the channel bed and trap sediment, this leads to a reduction in flow capacity
    4. Do not supply a year-round supply of riparian inputs (leaves etc) that natives do
    5. During autumn, drop massive amounts of leaves into the river, which decompose and reduce oxygen levels
    6. Create dense shade that stunts the growth of aquatic plants
    7. Fallen trees decompose quickly and therefore don't form snags for stream habitat.

All the points had some truth, but they were exaggerated and the flip sides ignored. This suggested that the facts were being interpreted to support the pre-determined view that willows were bad because they were exotic. A scientific approach would be to objectively consider what they could offer to certain river systems. These flip sides included:

1) Cause flooding - By blocking water flow, willows can cause flooding that spreads fertile soil over plains. Furthermore, when flooding causes water to soak into the landscape, it can seep out slowly to ensure flows continue longer into summer. (Red gums also contribute to flooding.) The Mulloon Creek farm is a real world example of how hydrating the landscape by using plants such as willows to slow flows has significant benefits for farmers. If done correctly, it can result in water flows in creeks leaving the farm being greater than water flows in creeks entering it.

2) Use more water - Although willows may use more water, their leaves provide a denser covering which lowers water temperatures and reduces evaporation. Some studies have shown dense shade can reduce water temperatures by up to 5 degrees celcius. (1)The reduction in evaporation saves water. Finally, by using more water, willows are very difficult to burn and therefore don't fuel bushfire like most natives.

3) Reduce flow rates - Although trapping sediment can reduce flow capacity, it also reduces erosion caused by high flow rates. Furthermore, slowing flow rate means that more water soaks into the willow area to hydrate the region. (Red gums can also reduce flow rate)

4) Provide riparian input for only half the year - It is true that willows don't provide a year-round riparian input like red gums; however, unlike willows, the leaves from red gums decompose slowly and can build up on the side of waterways for years on end. When floods occur, massive amounts of red gum leaves are washed into the wateways where their decomposition sucks oxygen out of the water causing deaths of fish, yabbies and shrimps. In short, willows don't cause the massive kills that are caused by gum trees after floods.

Blackwater Murray

Cod killed by red gums. One of the great ironies of floods in eucalypt rich areas is that they wash the leaves that have built up over the years into the water courses. This can lead to severe blackwater that kills aquatic life. Image source: Black water in Murray River 2011 https://www.abc.net.au/news/2016-10-26/black-water-in-murray-river-2011/7964102

5) Reduce oxygen levels in autumn - Although the willow drops massive loads of leaves during autumn, this is at a time when the water is cooler and can therefore hold more oxygen, and at a time when water levels are generally higher. Admittedly, there is a potential for blackwater under some conditions but they are rare. Furthermore, a year's growth falling into water over a number of months is still less of a threat than decade's growth being washed into a watercourse in a day as is the case with red gums.

6) Stunt aquatic plant growth - Although dense summer-time shade may stunt the growth of aquatic plants, these plants have the chance to recover in winter. Furthermore, many of these aquatic plants may be undesirable themselves. Some forms of algae can kill animals that drink from the water as well as fish in it. Lastly, when the aquatic plants die, they suck oxygen from the water and can kill everything.


Native fish killed by blue-green algae. Although willows may stunt the growth of aquatic plant life in summer, not all aquatic plant life is desirable. Blue-green algae outbreaks kill livestock and other aquatic life such as native fish. Willows can reduce the likelihood of the outbreaks by filtering nutrient rich run off before it reaches the water and reducing sunlight hitting the water. In contrast, eucalypts are poor at filtering nutrients out of the ecosystem. Image source: Darling River water quality declines with 10,000 native fish found dead from blue-green algae bloom. https://www.abc.net.au/news/2018-12-20/ten-thousand-fish-dead-as-darling-river-water-quality-worsens/10635730

7) Don't form snags - Willows do form snags but their snags just don't endure for as long as red gums as they decompose quickly. Nevertheless, they grow and die quickly so new snags are always being formed.

In addition to the flip side of the willow's supposed bad qualities, the scientists didn't consider other benefits over red gums such as:

  1. Protection from bushfire - Thick willows can act as a firebreak and will not burn like adjacent grass paddocks and native bush. Aside from not burning, the high moisture content of the willow leaves and their trunks cause them to decompose quickly so they don't build up as fuel. Furthermore, the dense summertime shade provided by leaves prevents undergrowth that can carry the fire. On the other hand, gums have high oil content and decompose slowly. As a result, most native plants along watercourses fuel fires. Not only does this kill most life in the water, but the watercourse has done nothing to slow or stop the fire.

  2. Protection from cormorants - The root systems of willows provide aquatic cover for small fish. Likewise, the cover provided by branches and leaves helps conceal fish from aerial predators. Fishing near willows is usually very successful due to the protection the trees provide from cormorants. Red gums don't provide the same protection for fish.

  3. Prevention of blackberry growth - The shade provided by willows helps stop growth by blackberry bushes that can take over when the willows are removed. Growth of blackberries makes river access for fishing very difficult.

  4. Lower water temperatures to help trout - The shade provided by willows can keep water temperatures lower. This is important for trout who can't tolerate the same temperatures as cod.

  5. Food for live stock - During winter time, willows loose their leaves and allow sunlight to reach the grass below. This grass can subsequently grow far more than it can under native plants that keep leaves through winter and which also release toxins that poison soil to inhibit competition. During summertime, the shade provided by the willows helps prevent grass being scorched. This grass provides food for native animals and livestock.

Fisherman have noticed declines in river quality following the removal of willows. To address these concerns, the Victorian Fisheries Authority promoted a study by John Morrongiello from the School of BioSciences, University of Melbourne. (9) The study was more of an argument that considered major environmental impacts rather than researched water temperatures or fish behavior following the removal of willows. Nevertheless, it concluded:

Willow removal is unlikely to have caused the observed declines in trout because it has neither been extensive enough, nor occurring in the upper parts of the catchment where the majority of stream shading should occur. ·

Willow removal can affect local scale shade, habitat and food for trout, but on a river scale the impact from willow removal on trout pales in significance against broader catchment issues like climate, drought, bushfire and topography.

The last 10 years have been particularly hot and dry, further amplifying the impacts of the bushfire. 2013 and 2014 were some of the hottest summers on record. These conditions are likely to become more common in the future.

Goulburn River Bushfire and Willow

It can be inferred from Morrongiello’s paper that he was not a fisherman. While he acknowledged that willows could cool temperatures in select pools, he argued that this was somewhat irrelevant because there weren’t enough willows to alter temperatures on a river scale. (The same argument could be made that there were not enough willows to warrant their removal in the first place because they couldn't alter oxygen levels on a river scale when their leaves fall in autumn.) If Morrongiello had been a fisherman, he would know that as temperature draws to 24 degrees, trout will congregate in the cooler pools. A shaded glide below rapids may see hundreds of fish desperately clinging to life while the river for kilometres either side is devoid of fish. Likewise, willows can slow water flow to produce gravelly beds that are rich in sand and sediment. Water can flow at a subterranean level beneath these beds and re-emerge as cooler springs in different parts of the river where trout will congregate. If the trout can survive in these final refuges, they can repopulate the river. For willows to form such refuges, they don’t need to be all along the river; they just need to be around a few select pools. With their close relationship to the river, fisherman understand this.

A 2004 study from western Australia did in fact illustrate the willows to alter temperatures in these pools. Specifically, it found temperatures increased by 4-5 C from patches of dense riparian shade to unshaded stream sections in 2nd order headwater streams. (2)

Although Morrongiello's reference to the trout declines being caused by hotter temperatures and more bushfires might have been true, it was also ironic as willows offer the best response to hotter temperatures and bush fires. Whereas native vegetation along a river will fuel a bushfire, willows will potentially stop it. There obviously weren't enough willows in the 2007 fires to save the river, but things may have been different had the rivers had the extensive protection provided by willows. Considering climate models predict hotter summers and more bushfires in the future, something needs to be done other than buying a Tesla or paying for a carbon offset while on an international junket. Morrongiello's advocated strategy seems to be to just let the rivers die as fisheries.

Recreational fishing is a multi billion dollar industry in Australia yet despite not having any research into how removing willows is impacting fish number, willow removal has continued. It seems the patriots who don't fish don't care what is happening to the fisheries as long as they can see some gum trees.

Comparison of willows to red gum/natives for long term agricultural and fishing benefits *

*Relies on speculation and first-hand fishing experience as almost no research on fish assemblages was done in the 30 years that government departments were planting willows and virtually none has been done in the 30 years government departments have been removing them.




Fish killing threats
Bushfire Stops fire Fuels fire
Blue-green algae Shade stunts growth and roots provide biofiltration of nutrients Little stunting of growth and biofilteration of nutrients
Blackwater Minor contribution every autumn Major contribution in flood years
Impact on fish health
Protection Significant protection for fish Snags provide good protection. Live trees less so.
Breeding May provide short-term spawning sites for cod Logs provide long-term spawning sites for cod
Food Some research indicates increase in biomass of prey ( ) Some research indicates increase in biodiversity of prey ( )
Water temperature Helps cool water in shaded pools up to 5 degrees (1) Little impact
Nuanced issues that depend on nature of stream    
Flood Can significantly block flows leading to flooding Live trees can block flows to contribute to flooding. Dead trees can block flows contributing to flooding.
Water useage Can transpire up to five times more water than a red gum when in stream(7 ) Transpire less water but does little to lower water temperatures to reduce evaporation
Livestock Food for livestock Not eaten by livestock
Flow rates Reduce flow rates Can reduce flow rates, but not as much as willows
Erosion Excellent erosion control Moderate erosion control
Toxins No toxins released Release toxins that kill grasses



If the issue is considered from a patriotic perspective, then there is a case to remove the willows. They takes the place of natives which many Australians see as a reflection of their identity as Australians. Furthermore, killing the ferals like willows are often community events that help Australians feel more connected to each other. Admittedly, perhaps waving the Australian flag might be a less destructive method to express patriotism; however, flag waving doesn't have the same community solidarity provided by killing ferals. Just as fisherman get an emotional high from catching a fish, many Australians get a high from killing a feral like a willow. That emotional high needs to be acknolwedged.

If the issue is considered from an agricultural perspective, then then it is a no brainer that the willows should stay. They reduce the chance of blue-green algae outbreaks that kill stock, help cause localised flooding to spread nutrients for pasture improvement, act as a feed source for livestock, slow water flows, and can be a firebreak.

If the issue is considered from a fishing perspective, it is nuanced as it depends on the favoured fish to target. Trout benefit from the cooler water temperatures. Once water temperatures reach 23C, they start dying. Exposed water bodies reach that temperature very quickly. It is very rare to hear of fisherman say that the removal of willows has increased the productivity of trout streams. Admittedly, sometimes willows make it difficult to access a river or fish along it.

Cod benefit from hardwood snags to breed but they also benefit from the protection from cormorants provided by willows. Because it is illogical to plant gums so cod have spawing sites 500 years in the future, perhaps dead gums could be put in rivers at prime locations. All aquatic life benefit from reduce incidences of blackwater floods, blue-green algae outbreaks and bushfire. If century long plans were implemented, it would be better to plant huon pine along water ways. It is native to Australia, wood decomposes very slowly so will form snags and is not flammable like eucalypts.

The ideal situation would be to manage biodiversity to ensure the ideal fish for the area has the ideal vegetation to ensure they can grow big for the fisherman. For the later, there is no sweeping policy only a need to look at the nature of river and decide what the fish need to increase in size.


Murrumbidgee in flood in 2011. Despite the massive volumes of water, the leaves from eucalypts still sucked oxygen out of the water leading to the death of fish and even yabbies seeking the water's edge. Not a willow in sight. At different times, the fish in the same site are at risk of blue-green algae outbreaks or bushfire fuelled by the eucalypts.

On balance, the willow offers a great number of benefits to many Australian ecosystems. If it didn't evolve in a foreign country, instead of scientists trying to argue what was wrong with it, they would be trying to find out what was right as foreign scientists have already done. The eradication of willows is the modern generation's answer to the 2000km long rabbit-proof fence that had been breached by rabbits before it was even finished in 1907; both stupid ideas driven by ideology that failed to achieve the purposes they stated they wanted to achieve.

1) Winsome Denyer 3rd December 2018 Soaking up Australia's drought

2)Jane Ryan Willow removal leads to mass soil erosion in north-west Tasmania  23 June 2014 https://www.abc.net.au/news/rural/2014-06-23/tch-willow-removal-disaster/5542492

3)Claudia Farhart March 16 2018
Lake Albert residents want their willow trees back in blue-green algae crisis The Daily Advertiser https://www.dailyadvertiser.com.au/story/5288126/lake-albert-residents-want-their-willows-back/

4) Sylvia Zukowski and Ben Gawne (2006) Potential Effects of Willow (Salix spp.) Removal on Freshwater Ecosystem Dynamics. A Literature Review. Link

5)Taking the long handle to willow https://www.dpi.nsw.gov.au/content/archive/agriculture-today-stories/ag-today-archives/april-2010/taking-the-long-handle-to-willow Accessed November 2019

6)Melissa Lyne April 13th, 2018 Managing our water-spoiling pests https://ecos.csiro.au/invasives-in-the-murray/

7)Calculating water savings from willow removal

8)Authors: Lizzie Pope, Ian Rutherford, Phil Price and Siwan Lovett Controlling Willows Along Australian Rivers: River and Riparian Land Management Technical Guideline, Land and Water Australia https://library.dbca.wa.gov.au/static/FullTextFiles/070631.pdf Accessed December 2019

9)John Morrongiello Streamside vegetation change, water temperature and trout School of BioSciences, University of Melbourne Victoria https://vfa.vic.gov.au/__data/assets/pdf_file/0007/341584/Bankside-vegetation-and-water-temperature-study-summary.pdfAccessed December 2019


Agriculture Victoria risk analysis

Invasive ferals


Carp and Trout
A tale of two ferals

New hope for Cane Toads
The many unknown predators of the toad

A fence almost 2,000 km long to keep rabbits out of WA? Sounds like a great idea! If it doesn't work, we'll build another one!

The Willow
How a change in its status from asset to weed led to fish kills with blackwater and blue-green algae outbreaks

To bait dingos?
Should the health of the ecosystem be considered or just the kennel club registration?

Koala control
What to do about the "koala plague" on Kangaroo Island

Apex predator in Australia. Confined to urban areas in America.

Environmental values

Environmental problems
How money and ideology shapes environmental "science."

Australia's Stockholm Syndrome with gum trees.

The Kangaroo industry
Should we eat skippy?

Climate change in Australia
Australia was once covered in rainforest. Could it be again?

The dark side of sustainable environmental policies

Native pets
Why no pet wombats?




Australian environmental science is defined by an ideology that is not unlike a prison warden. There, the scientists are not seeing themselves as part of the ecosystem, but as masters over it; protecting the rights of the species that they say have rights and killing those that they say do not…but inevitably killing both.

"It was always seen as desirable to remove or cull the introduced species. We also need to ask whether it was possible to do so, how it should be done, whether it could have unintended consequences and what it would cost? I don't think anyone really asked those questions." Physicist John Reid - 2012